$40000 Budget, need 4 machines for university students.

[killahbeeze]

This is an odd one for me, having spent several years building a CNC for personal use, but a professor recently approached me about installing several of these machines for the department, with a sizable budget. I need advice on whether or not to: design & build, utilize kits, or buy four pre-assembled.

It will be for general student use, and there's already a very nice machine available, so really, it's just filling a middle ground for interested students, with non-critical projects. They seemed to be interested in the LPKF Mills, but I've never been one for throwing money at it. Any help?

[Bob La Londe]

All mills? If so consider 2 high speed spindle machies, and 2 normal speed spindle machines.

[killahbeeze]

What would the advantage of 2 different spindle speeds be, over an adjustable spindle controller?

[Bob La Londe]

There aren't too many spindels that will go from say 30 RPM to 30000 RPM.

100-3500 or possibley 6000 is pretty common.

8000-24000 is pretty common.

10000-60000 is modestly common.

My Hurco is set for a low speed of 96 and a top speed of 3000 with a 5HP motor. Thats great for big cutters and heavy cutting, but its production rate would be worse than carving it out with a hammer and chisel though for the tiny .125 down to .03125 cutters I use 3D carving in aluminum. My Taig will run circles around the Hurco for production rate with those small cutters.

You have the opportunity to get machines for students that will give the experience in both high speed maching and in heavy machining.

At the risk of sounding crass, why did you think "fixed" speed?

[Bob La Londe]

The other thing to think about is control. Might be cool to have all different machines and all different controls to give them "real world" experience. LOL. One running Mach 3, one running Centroid, one running Fannuc, maybe one running old Bridgeport code etc... LOL.

Actually, that's a bit ridiculous. Some standardiization would certainly be needed if only not to drive the instructors mad when a student has a problem, but its a fun thought.

[doorknob]

I'm not sure from your description - do they all have to be PCB mills, or can some of them be more general machines?

[txcncman]

Students should not be touching CNC machines until they can reasonably produce parts on manual machines.

[Bob La Londe]

How do you reasonabley produce a PCB on a manual machine? It would easier to just draw it with a pen and etch it in acid. I understand the whole "You must pay your dues first," thinking but sometimes life deals you different cards.

[underthetire]

I'd be super careful building anything for students. It will have to meet all OSHA, nfpa, ANSI standards, and even then someone gets hurt they will go after you. You better have liability insurance. I've seen this first hand with a major builder, even though the student was totally at fault, he won simply because "he wasn't properly trained in the possibility of injury". Bunch of crap I know, but it happens all the time.

[killahbeeze]

Sorry for not specifying, they are to be primarily for PCB use. After building a 7x7 Zen Toolworks, we pitched the idea for building one (at a cost of $1000) for our IEEE chapter. The instructor would like to actually make it a lab requirement however, so he's thrown a little more money at it. I am also very worried about student misuse, but it's no skin off of my back, so my main concerns are a reliable, easy to operate product.

Technicalities aside, where do I begin? What would you do with $10000 to build a machine? Some of the commercial grade ones look nice, but I would not trust them to a lab full of sophomores, let alone me. If anyone knows of a high-end kit, that would be greatly appreciated. The ability to swap out parts as needed, and pair it with my choice of drivers/ software would be a big plus.

[Jay C]

I have no experience with any of these, but they all cater to PCB market. It's been shown repeatedly that you can use a general CNC router with a 30K RPM spindle (I use a Bosch Colt) to do it too, but I suspect you are looking for a turn key system with a long life and support.

AccurateCNC, Inc.
LPKF Laser & Electronics: Board Router
PCB Milling Machine System,PCB Prototyping Machine
T-Tech, Quick Circuit Prototyping Systems

FWIW.

[killahbeeze]

I've been eying the accurate CNC for a while now, it looks to be a pretty slick system. A lot of the others options (at least in our price range) give the impression that with a little bit of work, a similar system could be had for half of the cost.

Do you know if all of these systems require proprietary software to operate?